Cricoid ring: Shape, size, and variability in infants and children

Area of Science:

• Pediatric airway anatomy
• Medical imaging techniques

Background:

• Accurate pediatric endotracheal tube (ETT) selection requires understanding cricoid ring dimensions.
• Previous studies utilized various methods like MRI and bronchoscopy.
• Computed tomography (CT) offers a precise approach to pediatric airway assessment.

Purpose of the Study:

• To determine the shape, size, and configuration of the pediatric cricoid ring.
• To analyze age-related variations in cricoid ring morphology.
• To provide data aiding in appropriate ETT selection for pediatric patients.

Main Methods:

• Retrospective review of 130 pediatric CT scans (age 1 month to 10 years).
• Scans were from patients undergoing evaluation unrelated to airway symptoms.
• Anteroposterior (AP) and transverse (T) diameters of the cricoid ring were measured.

Main Results:

• The cricoid ring is typically round in children >1 year (T/AP ratio 0.98-1.01).
• Infants (1-12 months) exhibit an elliptical cricoid ring, with AP diameter larger than T (T/AP ratio 0.95).
• A statistically significant difference in diameters was noted in infants (P < 0.05).

Conclusions:

• Pediatric cricoid rings are round in children over 1 year old.
• Infants present with an elliptical cricoid ring, narrower in the transverse axis.
• CT imaging provides accurate cricoid ring configuration data, crucial for ETT selection in infants.